backbone：courage and determination
最基本的意思是“脊柱”“脊骨”，也常被引申表示“支柱”（比如支柱产业中的“支柱”）和“勇气/胆量”。我们今天学习它作“胆量”的意思。它作“胆量”时是不可数名词，可以替换我们常用的“courage”。
He has a crush on Sarah, but doesn't have the backbone to ask her out.（”have a crush on somebody“是固定表达，意思是迷恋某人。）
Nobody on the Chongqing bus had the backbone to intervene and prevent the middle-aged woman from assaulting the driver. If somebody did, the story would have turned out very differently.
1）He didn’t have the backbone and gave up the chance of applying for a scholarship at last.
2)I need to have the backbone to improve my studying method.
